Production of seams for knit goods



May 4, 1937.

N. V. CHRISTENSEN PRODUCTION OF SEAMS FOR KNIT GOODS Original Filed Jan. 15, 1935 2 Sheets-Sheet l INVE NTOR: VL'hn m m m TTORNEYS.

May 4, 1937. N. v. CHRISTENSEN PRODUCTION OF SEAMS FOR KNIT GOODS 2 Sheets-Sheet Original Filed Jan. 15, 1935 INVENTOR:

risicnsem Nbrman L/Ch BY Q 1 TTORNEYS.

Patented May 4, 1937 UNITED STAT PATENT OFFICE.

Union Special Machine Company,

Chicago, 111.,

a corporation of Illinois Application January 15, 1935, Serial No. 1,885 Renewed December 5, 1935 Claims.

This invention relates to the seaming of knit goods, and has for its end the production of a covered seam of attractive appearance and comparatively flat, having greater resistance to lat eral pull in proportion to the quantity of thread employed than is found in other seams of this character.

. The seam is a composite one, including as elements a line of primary stitching and two lines of a secondary covering stitching, both, however, produced in one operation, and functioning to reinforce each other both during and after their formation. It is characterized by high resistance to lateral strains which tend to pull apart the seamed fabric sections, by reason of the fact that the primary and secondary stitches resist such strains simultaneously and collectively and not successively and separately; for if in such a composite seam the resistance of one element is overcome by breakage before the resistance of the other comes into full play, the strength of the seam is no greater than that of the stronger of the two elements, whereas in my scam the resistance is equal to their combined strength.

My invention is useful in connection with knit goods seamed in tubular'formation upon a feedoff-the-arm sewing machine and is carried out with production of the covering seam on the side of the fabric uppermost during the seaming operation whereby the deflection of trimmings is facilitated. As my invention is usually practiced I form the tube with the wrong side of the fabric outside; and then after the trimmings are deflected' and theunion completed the tube is reversed sothat the cover threads are inside the tube.

In the accompanying drawings:

Fig. I is a fragmentary perspective view of my improved covered flat lap seam in one form.

Fig. II is a fragmentary perspective view of the stitching employed in connection with the seam of Fig. I. I

Fig. III is a diagrammatic cross section taken as indicated by the arrows III--III inFig. I.

Figs. IV, V and VI are viewscorresponding to Figs. I,- II and- III showing an alternative embodiment of my invention and Figs. VII and VIII are fragmentary perspective views showing respectively the two forms of covered lap seams in the process of formation.

In Figs. I, II and III the numerals I and 2 designate the two fabric portions which are to be united. The portion 2 is formed with a marginal fold 3 which is lapped by a corresponding unfolded margin 4 of the portion l with the edges 5 and B of said margins coinciding. This lap joint is secured by a primary line of chain-stitching 1, approximately midway of the lap. The needle thread loops 8 of this stitching completely penetrate all three of the fabric thicknesses as shown in Figs. II and III, said loops 8 being engaged by loops 9 formed from a looper thread. The penetration of this line of needle thread loops is far enough back from the edges of the lapping margins of the fabric sections to afford firm anchorage.

The stitching l is reinforced and the trimmed edges covered by a secondary stitching which includes two parallel lines In of chain-stitches, one at each side of the lap joint. The needle loops ll of one line H! of this secondary stitching penetrate only the fabric section I; while the needle loops ll of the other line 10 penetrate only the fabric section 2. As shown in Figs. I and II, the needle loops H are engaged with the loops [2 of a' single looper thread which passes back and forth between the two parallel lines Id of the secondary stitching, thereby connecting said lines laterally, with the transverse cover segments l3 and Hi overlying the lap joint and crossing the primary stitching 1 as shown in Figs. I and III.

. In producing a seam such as described incident to connecting opposite edges of a tube formed from a single piece of knit fabric, the piece is folded into the form of a tube as shown in Fig. VII around the arm of a sewing machine with the face of the fabric at the inside, and advanced in the direction of the arrow in the illustration in such manner that margins l5 and l6 along the opposite edges of the fabric are caused to abut in upstanding relation. The marginal edges are then trimmed, and the trimmings l1 and I8 are disposed all by lateral deflection as shown, thereby leaving the narrow trimmed coincident margins 3 and 4 with aligned edges. Immediately thereafter, the trimmed margins 3 and 4 are progressively turned over laterally as shown at 9 without disturbing their alignment, until they lie flat against the fabric section 2, whereupon the primary line of chain-stitches l passing through the three thicknesses of fabric is formed to secure the fold. The lines H) of the secondary covering stitching are preferably formed concurrently with the primary stitch line I, but if desired or found convenient in practice, they may be formed subsequently by a separate operation. After com pletion of the seam, the tube is reversed so that the cover stitching is brought to the inner side of the tube. The seam thus presents a neat appearance at the outer side of the tube.

As shown in Figs. I, II, III and VII the transverse covering threads overlie the primary stitching, but in the alternative embodiment of my invention illustrated in Figs. IV, V, VI, and VIII the crosswise looper yarn segments |3a., [4a, connecting the parallel stitch lines Illa, engage or underlie the loops 9a of the central line la. In order to obviate the necessity for more lengthy description, the corresponding parts in these figures have been identified with the same reference numerals previously employed except for the addition, in each instance, of the letter a as a distinction. The method followed in forming the alternative form of seam is identical with that described of the first form and will be obvious from Fig. VIII, except in that the stitch lines To and ma must be concurrently formed for lnterengagement of the segments l3a and Ma of the looper thread with the loops 9a.

It is also within the purview of my invention to cause the covering threads, if desired, to engage loops of the primary stitching rather than to overlie or underlie said loops.

Among the advantages of the seam thus described is that Without sacrificing the strength of the seam the lap joint is left uncovered on the lower side (the side not seen in Figs. I, IV, VII and VIII), rendering it very inconspicuous. Cross laid covering threads such as have sometimes been employed to cover the needle thread side of seams of this general character do not add appreciably to the strength of the seam because the cross threads are tightly drawn and broken by lateral pull before the resistance of the central line of stitching comes into operation. In the seam which I have produced the central stitching, because completely penetrating all three thicknesses of fabric, resists lateral strain simultaneously with the resistance of the covering thread. Another advantage of this seam is the neat appearance presented by the underside of the lap due to the folded edge of the underlying fabric section.

Having thus described my invention, I claim:

1. The method of uniting knit fabric sections which consists in placing such sections in juxtaposition with upstanding edges abutted; trimming the upstanding edges and deflecting and trimmings; folding both trimmed edges down flat upon one of the sections with production of a three thickness overlap; uniting these three thicknesses before any displacement occurs by a line of stitching which completely penetrates all three thicknesses, and by a simultaneous operation imposing a covering thereupon comprising two lines of stitching united by covering threads, one line of said covering stitching passing through each single thickness of fabric close to the edge of the overlap, the needle thread entering the fabric from beneath while a covering thread is crossed from one side to the other to cover the freshly trimmed edges of the fabric, whereby any lateral strain tending to pull the fabric sections apart is resisted simultaneously and collectively by both the central line of stitching and the covering stitching.

2. The method of uniting opposite edges of a piece of knit fabric formed into a tube, which consists in rounding the piece with the face of the fabric inside and with upstanding edges abutted; trimming the upstanding edges and deflecting the trimmings away from the tube; folding both trimmed edges down fiat upon one side of the tube with production of a three thickness overlap; uniting these three thicknesses, before any displacement occurs, by a line of stitching which completely penetrates and firmly unites all three thicknesses, and, by a substantially simultaneous operation, applying a covering which comprises two lines of chain-stitching one upon each single thickness of fabric close to the edge of the overlap, the needle threads of these lines of stitching entering the fabric from beneath while the covering thread is crossed from one line of stitching to the other to cover the freshly trimmed edges of the fabric before they can ravel out; and finally reversing the tube to bring the face of the fabric to the outside.

3. The method of uniting fabric sections which consists in placing such sections in juxtaposition with upstanding margins abutted; laterally folding both margins flat into superimposition upon one of the fabric sections with formation of a three thickness overlap; and uniting the fold by a line of chain stitches penetrating all three thicknesses of said fold and by a simultaneous operation imposing a covering comprising two outer lines of stitching united by covering threads, one line of said cover stitching passing through each single thickness of the fabric close to the edge of the overlap with a cover thread passing crosswise over the fold between the outer stitch lines.

4. The method of uniting fabric sections which consists in placing such sections in juxtaposition with upstanding edge margins abutted, laterally folding the edges down flat in superimposition upon one of the sections with formation of a three thickness overlap; uniting the three thicknesses at the fold by a line of stitching passing completely through them, and by a simultaneous operation imposing a covering over the fold comprising two lines of stitching, one at each side of the fold passing through each single thickness of fabric close to the edge of the overlap with a cover thread passing crosswise between the outer lines of stitching and beneath the stitches of the first mentioned line.

5. The method of uniting fabric sections which consists in placing such sections in juxtaposition with upstanding margins abutted, trimming the upstanding margins, laterally folding the trimmed margins flat into superimposition upon one of the fabric sections with formation of a three-thickness overlap, uniting the fold by a line of chain stitches penetrating all three thicknesses of said fold, and by a simultaneous operation imposing a covering comprising two outer lines of stitching united by covering threads, one line of said cover stitching passing through each single thickness of fabric close to the edge of the overlap with a cover thread passing cross-wise of the fold between the outer stitched lines.

N. V. CHRISTENSEN. 

